Stellar gas flows into a dark cluster potential at the Galactic center

Fulvio Melia, Robert Coker

Research output: Contribution to journalArticle

18 Citations (Scopus)

Abstract

The evidence for the presence of a concentration of dark matter at the Galactic center (GC) is now very compelling. There is no question that the stellar and gas kinematics within ≈0.01 pc is dominated by underluminous matter in the form of either a massive black hole, a highly condensed distribution of stellar remnants, or a more exotic source of gravity. The unique, compact radio source Sgr A* appears to be coincident with the center of this region, but its size (less than about 6 × 1013 cm at λ7 mm) is still significantly smaller than the current limiting volume enclosing this mass. Sgr A* may be the black hole, if the dark matter distribution is pointlike. If not, we are left with a puzzle regarding its nature and a question of why this source should be so unique and lie only at the GC. In this paper, we examine an alternative to the black hole paradigm, that the gravitating matter is a condensed cluster of stellar remnants, and study the properties of the GC wind flowing through this region. Some of this gas is trapped in the cluster potential, and we study in detail whether this hot, magnetized gas is in the proper physical state to produce Sgr A*'s spectrum. We find that at least for the GC environment, the temperature of the trapped gas never attains the value required for significant GHz emission. In addition, continuum (mostly bremsstrahlung) emission at higher frequencies is below the current measurements for this source. We conclude that the cluster potential is too shallow for the trapped GC wind to account for Sgr A*'s spectrum, which instead appears to be produced only within an environment that has a steep-gradient potential like that generated by a black hole.

Original languageEnglish (US)
Pages (from-to)750-760
Number of pages11
JournalAstrophysical Journal
Volume511
Issue number2 PART 1
StatePublished - Feb 1 1999

Fingerprint

gas flow
gas
dark matter
gases
potential gradients
kinematics
high temperature gases
radio
gravity
bremsstrahlung
gravitation
continuums
temperature
distribution

Keywords

  • Black hole physics
  • Galaxy: center
  • MHD

ASJC Scopus subject areas

  • Space and Planetary Science

Cite this

Stellar gas flows into a dark cluster potential at the Galactic center. / Melia, Fulvio; Coker, Robert.

In: Astrophysical Journal, Vol. 511, No. 2 PART 1, 01.02.1999, p. 750-760.

Research output: Contribution to journalArticle

Melia, Fulvio ; Coker, Robert. / Stellar gas flows into a dark cluster potential at the Galactic center. In: Astrophysical Journal. 1999 ; Vol. 511, No. 2 PART 1. pp. 750-760.
@article{00a0586752904607b1113d7a640c83cd,
title = "Stellar gas flows into a dark cluster potential at the Galactic center",
abstract = "The evidence for the presence of a concentration of dark matter at the Galactic center (GC) is now very compelling. There is no question that the stellar and gas kinematics within ≈0.01 pc is dominated by underluminous matter in the form of either a massive black hole, a highly condensed distribution of stellar remnants, or a more exotic source of gravity. The unique, compact radio source Sgr A* appears to be coincident with the center of this region, but its size (less than about 6 × 1013 cm at λ7 mm) is still significantly smaller than the current limiting volume enclosing this mass. Sgr A* may be the black hole, if the dark matter distribution is pointlike. If not, we are left with a puzzle regarding its nature and a question of why this source should be so unique and lie only at the GC. In this paper, we examine an alternative to the black hole paradigm, that the gravitating matter is a condensed cluster of stellar remnants, and study the properties of the GC wind flowing through this region. Some of this gas is trapped in the cluster potential, and we study in detail whether this hot, magnetized gas is in the proper physical state to produce Sgr A*'s spectrum. We find that at least for the GC environment, the temperature of the trapped gas never attains the value required for significant GHz emission. In addition, continuum (mostly bremsstrahlung) emission at higher frequencies is below the current measurements for this source. We conclude that the cluster potential is too shallow for the trapped GC wind to account for Sgr A*'s spectrum, which instead appears to be produced only within an environment that has a steep-gradient potential like that generated by a black hole.",
keywords = "Black hole physics, Galaxy: center, MHD",
author = "Fulvio Melia and Robert Coker",
year = "1999",
month = "2",
day = "1",
language = "English (US)",
volume = "511",
pages = "750--760",
journal = "Astrophysical Journal",
issn = "0004-637X",
publisher = "IOP Publishing Ltd.",
number = "2 PART 1",

}

TY - JOUR

T1 - Stellar gas flows into a dark cluster potential at the Galactic center

AU - Melia, Fulvio

AU - Coker, Robert

PY - 1999/2/1

Y1 - 1999/2/1

N2 - The evidence for the presence of a concentration of dark matter at the Galactic center (GC) is now very compelling. There is no question that the stellar and gas kinematics within ≈0.01 pc is dominated by underluminous matter in the form of either a massive black hole, a highly condensed distribution of stellar remnants, or a more exotic source of gravity. The unique, compact radio source Sgr A* appears to be coincident with the center of this region, but its size (less than about 6 × 1013 cm at λ7 mm) is still significantly smaller than the current limiting volume enclosing this mass. Sgr A* may be the black hole, if the dark matter distribution is pointlike. If not, we are left with a puzzle regarding its nature and a question of why this source should be so unique and lie only at the GC. In this paper, we examine an alternative to the black hole paradigm, that the gravitating matter is a condensed cluster of stellar remnants, and study the properties of the GC wind flowing through this region. Some of this gas is trapped in the cluster potential, and we study in detail whether this hot, magnetized gas is in the proper physical state to produce Sgr A*'s spectrum. We find that at least for the GC environment, the temperature of the trapped gas never attains the value required for significant GHz emission. In addition, continuum (mostly bremsstrahlung) emission at higher frequencies is below the current measurements for this source. We conclude that the cluster potential is too shallow for the trapped GC wind to account for Sgr A*'s spectrum, which instead appears to be produced only within an environment that has a steep-gradient potential like that generated by a black hole.

AB - The evidence for the presence of a concentration of dark matter at the Galactic center (GC) is now very compelling. There is no question that the stellar and gas kinematics within ≈0.01 pc is dominated by underluminous matter in the form of either a massive black hole, a highly condensed distribution of stellar remnants, or a more exotic source of gravity. The unique, compact radio source Sgr A* appears to be coincident with the center of this region, but its size (less than about 6 × 1013 cm at λ7 mm) is still significantly smaller than the current limiting volume enclosing this mass. Sgr A* may be the black hole, if the dark matter distribution is pointlike. If not, we are left with a puzzle regarding its nature and a question of why this source should be so unique and lie only at the GC. In this paper, we examine an alternative to the black hole paradigm, that the gravitating matter is a condensed cluster of stellar remnants, and study the properties of the GC wind flowing through this region. Some of this gas is trapped in the cluster potential, and we study in detail whether this hot, magnetized gas is in the proper physical state to produce Sgr A*'s spectrum. We find that at least for the GC environment, the temperature of the trapped gas never attains the value required for significant GHz emission. In addition, continuum (mostly bremsstrahlung) emission at higher frequencies is below the current measurements for this source. We conclude that the cluster potential is too shallow for the trapped GC wind to account for Sgr A*'s spectrum, which instead appears to be produced only within an environment that has a steep-gradient potential like that generated by a black hole.

KW - Black hole physics

KW - Galaxy: center

KW - MHD

UR - http://www.scopus.com/inward/record.url?scp=0033076681&partnerID=8YFLogxK

UR - http://www.scopus.com/inward/citedby.url?scp=0033076681&partnerID=8YFLogxK

M3 - Article

VL - 511

SP - 750

EP - 760

JO - Astrophysical Journal

JF - Astrophysical Journal

SN - 0004-637X

IS - 2 PART 1

ER -